This paper presents the development and characterization of ambipolar monolayer WSe₂ devices with electrically tunable PN junctions. The devices are fabricated using a split-gate technique, allowing for the precise control of carrier density and the creation of both PN and NP diodes. The PN diodes exhibit ideality factors better than 2 and show photodetection responsivity of 210 mA/W under light excitation, with a peak external quantum efficiency of 0.2% for photovoltaic power generation. Additionally, the devices can function as light-emitting diodes, emitting light at a peak wavelength of 752 nm. These findings highlight the potential of monolayer WSe₂ for a wide range of optoelectronic applications, including photodetectors, solar cells, and flexible, transparent electronic devices. The study also discusses the advantages of monolayer WSe₂ over bulk materials in terms of flexibility, transparency, and direct band gap, making it a promising material for next-generation optoelectronic devices.This paper presents the development and characterization of ambipolar monolayer WSe₂ devices with electrically tunable PN junctions. The devices are fabricated using a split-gate technique, allowing for the precise control of carrier density and the creation of both PN and NP diodes. The PN diodes exhibit ideality factors better than 2 and show photodetection responsivity of 210 mA/W under light excitation, with a peak external quantum efficiency of 0.2% for photovoltaic power generation. Additionally, the devices can function as light-emitting diodes, emitting light at a peak wavelength of 752 nm. These findings highlight the potential of monolayer WSe₂ for a wide range of optoelectronic applications, including photodetectors, solar cells, and flexible, transparent electronic devices. The study also discusses the advantages of monolayer WSe₂ over bulk materials in terms of flexibility, transparency, and direct band gap, making it a promising material for next-generation optoelectronic devices.